The increase in demand for mobile communication devices and in particular aeronautical satellite communication devices, which may be installed on light aircraft, has required that these devices become smaller. One of the larger components in these devices is the antenna. Antennas used for this type of communication are often large diameter helical antennas. The installation of these devices on light aircraft has thus created a need for smaller antennas and lower wind resistance. Further desirable qualities of a helix antenna for mobile communications devices would be reduced axial ratio, improved gain, wide bandwidth and reduced beamwidth.
Conventional helical antennas having the required gain, beam width and axial ratio performance would not fit into the space allotted within a radome of an aircraft or similar restricted space. It is also known to improve the gain of a helix antenna by tapering the helix pitch along the length of the antenna in the axial direction. This also provides reduced beam width.